Hi.
CF is 3855,0 kHz (FAX = FSK).
Be aware that all FSK (FAX, RTTY, SITOR-A/-B, DSC, NAVTEX etc.) signals have a center frequency ALWAYS in the middle between high and low "tone" (Frequency). You may receive it in USB (with speciall offset) or CW (with correct BFO tune). But as it is a frequency modulated signal the CF is always between "mark" and "space" (low and high "tone" or frequenc).
Hope this helps.
